Upgrading OpenWrt

GPIO

Bootstrap HIGH or LOW means that during bootstrap process (first few seconds as device is turned on) these pins need to be in that state. If pins are not in requred state then device will not boot correctly.

Worry free GPIO pins™:
If you have some DIY project use GPIO pins 18, 19, 20, 21, 22 and 23 without any worries, these pins are not used during booting. Other GPIO pins are not suitable for use if you don't know exactly what you are doing because they are used during boot process (bootstrap).

LED GPIO LED0 (GPIO0), LED2 (GPIO13) and LED3 (GPIO14) are being used by kernel module "leds_gpio" - You can use them after removing leds_gpio module by rmmod, or removing it permanently from /etc/modules.d